Automatic brake adjustment



Mmh 26, 1940.

vG. v'. MABRrrov AUTOMATIC BRAKE ADJUSTMENT Filed June 25,A 1939 Wre-essi l5 diierent dimensions and designs. The invention member I6, which isanchored xedly by two of 15 55 purpose each brake shoe is provided withan authe curved edge of the web l.. And since this u PatentedMsi.26,194o 2,195,178.

UNITED STATES PAT-ENT OFFICE l i 2,195,178 A AUToMATIc BRAKE ADJUSTMENTGuido V. Mabrito, Chicago, Ill.

Application June 2s, 1939, serial No. 281,178 1o claims. (ci. iss-79.5)

This invention relates to vehicle brakes, and tomatic adjusting devicewhich includesa wedge particularly to the type designed for automotivemember I having a transversely extending poruse. One object of theinvention is to provide tion II at one end and'a transversely extendingmeans for adjusting the brake shoes automatical- -portion I2 at theother end, with notches I Ia and 5 1y to compensate for wear of thebrake linings I2a formed in said portions respectively so that 5 so asto maintain a substantially uniform opthese notches may engage orstraddle the curved erating clearance at all times. Another object inneredge of the web 4 of the brake shoe. How.- is to provide a simple anddependable mechanism ever, the notches do not bear against the brakewhich shall be economical to manufacture and shoe web because the memberI0 carries a curved l0 which may be readily installed in existingmechspring I3 whose end portions I4 engage respec- 10vr anisms ofconventional type without undue altively in the notches II and |25,while a convex I teration of the same. A further object is to profaceportion of the curved Spring bears against vide -a device in which aminimum 4of variation the edge of the web 4. The opposite edge I5 of isrequired to adapt it to brake structures of the wedge member bearsagainst an abutment consists in certain features and elements of conthebolts 9 and Which is formed With a' bent lug struction as herein shownand described 'and I1 having at notch I'Ia intov Which the edge I5 asindicated bythe claims. of the wedge member IIJ ts slidably. A light Inthe drawing: i spring IB extends from a hole I9 in the wedge Fig. lis avertical section of a conventional member III to a hole 20 in the web ofthe brake 20 automobile brake showing the brake shoes and shoe So as toexert a constant force longitudioperating means therefor, together withelements 'nelly 0f the Wedge member.

constituting this invention as applied thereto. When lvlO under Stressthe Spring member I3 Fig.v 2 is a partial transverse section taken iscurved somewhat more sharply than the eon' radially as indicated at line2-2 on Fig. 1. vtour` of the inner edge of the brake shoe web 4, 25

Fig. 3 is a perspective view of the wedge membut when, it is installedin the wedge member ber of the adjusting device. y I0 and in contactwith the web of the brake shoe, Fig. 4 is a perspective view of thespring bearthe Spring I3 Will be ileXed by the tension 0f ing member forthe wedge, ythe spring 8 until it conforms to the curvature Fig. 5 is aperspective view of the abutment 'of the edge of the web 4. Then, as thebrakes 30 member for the adjusting device, are applied,.the spring I3will tend to assume In the conventional brake structure chosen for ltsDOImel curvature With Only Dart 0f its length purposes of illustrationthe brake drum I, which in COIltaCt With the edge 0f the Web 4. Suchconmay be understood as carried by the vehicle wheel, fleet Will bemaintained if the mOVement of the is shown with its flange adjacent thefixed anbrake shoe, 3S it iS applied against Iil'le drum I, 35 chorplate 2, upon which the brakemeehanism does not exceed a predeterminedamount, say, is mounted. This mechanism includes brake about 011elthirty-SeCOnd 0f en inch.` But when shoes 3 having web pori-,ions 4which are pivoted the brake lining I becomes worn so as to increase at 5upon the anchor plate 2. A hydraulic cylthe amount of this clearance, itwill be seen inder is shown at 6, arranged for operating the that thenecessary movement of the brake shoe 40 brake shoes to press theirfriction linings 1, into Will Carry the edge 0f the Web 4 out of contactcontact with the brake drum I in the usual man- Withvthe CuIVed SpringI3.. This Will permit the 11er- A retracting Spring 8 is convenientlyartension of spring I8 to slide the wedge member ranged with its endsconnected to the-webs 4 of I0 in a direction to take up the increaseclearance the two brake shoes S0 as to draw them out of so that when thebrakes are again released the 45 contact with the drum I when theactuating pres- ShOe Cannet move away from the drum I by sure isreleased. The anchor plate is secured to more than the desired amOum?-the nxed axle structure by means of the usual It will be noted that thepull of the spring I8 bolts 9. includes a component in the direction ofcon- It is desirable to maintain a uniform, normal vergence of the edgel5 of the wedeemember I0, clearance between the friction linings 1 andthe and the chord of the arc to which the curved opposing surface of thebrake drum I, so that spring member I3 conforms; in other words, the theoperating movement of the brake pedal shall spring tends to urge a widerportion of the remain uniform and within safe limits. For this wedgebetween the notched abutment lug I1 and spring tension is exertedcontinuously, it will serve to shift the wedge I0 very gradually inresponse to the gradual wear of the brake lining 1.

In the construction illustrated both brake shoes are shown tted with thecompensating wedges I0 and related parts, which, however, operateindependently of each other in accordance with the wear experienced bythe individual brake linings 'i on the two brake shoes.

It will be evident that the parts III and I6 may be quite economicallymanufactured as stampings, castings or forgings, and that the part 1 maybe of standard design, even though the contour and dimensions ofthe`=brake shoes to which it is applied may vary through considerablelimits. The part I6 must, of course, be made to iit the particularanchor plate and the spacing of the bolts 9 which are to secure themember. And the spring members. I3 will be carefully shaped so that theamount by which they must be flexed from normal curvature to conform tothe shape of the edge of the web 4 shall correspond with the desirableamount of. brake clearance; these spring members I3 may thus be madeinterchangeable in the notches of the wedge member II) to adapt it toany particular design of brake shoe.

When the brakes are supplied with automaticl adjusting devices embodyingthis invention the maintenance of a standard clearance will operate toequalize the braking action on all wheels oi the vehicle, thusincreasing the safety of operation of the vehicle.

As an additional safeguard, the Wedge Amembers III are formed withshoulders lia, which will eventually encounter the lugs I'I as theWedges follow in the direction in which they are drawn by springs I8.The shoulders |51@L thus dene a limit beyond which the wear of the brakelinings will not be taken up by the Wedges IIB, and at this point therewill be no further compensation for wear ofthe brake lining and theoperating pedal will require a longer stroke in applying the brakes.This will aord a definite warning to the driver that his brakes needrelining, and this warning Will come before the rivets or other metalparts of the brake shoes have begun to score the brake drum injuriouslyby direct contact therewith.

Thus the installation of these adjusting devices will protect the publicby increasing the safety in operation of the vehicle; it will protectthe owner of the vehicle against expensive repairs and replacements andagainst accidents which might occur by reason of faulty brakes; and itwill rather tend to improve business in the repair and maintenance ofbrake linings in that the driver is duly warned of the need forreplacement as it occurs, and is not so likely to continue using thebrake linings after they have become excessively Worn.

While there is shown and described herein certain specic structureembodying the invention, it will be manifest to those skilled in the artthat various modifications and re-arrangements of the parts may be madewithout departing from the spirit and scope of the invention, and thatthe same is not limited to the particular form herein shown anddescribed, except in so far as indicated by the appended claims.

I claim:

l. In a vehicle brake, in combination with a brake drum and a brake shoewhich includes a flange to support a friction lining and a web with aconcavely curved edge, a xed abutment spaced from said edge of the web,a wedge interposed between said edge and the abutment, said wedge havinga spring face normally of. greater curvature than the edge of the webbut yieldable to conform thereto and having its opposite face inslidable engagement with the abutment, said opposite face extending inconvergent relation to the chord of that portion of the curved Web whichthe spring face engages, and spring means urging said wedge in thedirection of convergence of its said faces.

2. In the combination defined in claim 1, said spring face normallyexerting sufficient friction against the edge of the brake shoe web andthe abutment to oppose the force of said spring means and preventmovement of the Wedge in the direction of convergence of. its faces.

3. In the Combination deined in claim l, the deflection of said springface from its normal curvature for conformity to the edgeA of the brakeshoe affording a measure of permissible clearance between the brake shoeand the drum whereby, when such clearance is exceeded, the

spring means shifts the wedge to take up the l excess clearance.

4. In a vehicle brake, in combination with a brake drum and a brake shoewhich includes a ilange to support a friction lining and a web with aconcavely curved edge, together with a retracting spring normallyholding said brake shoe and its lining away from the drum, a fixedabutment spaced from saic cur-ved edge of the web, a Wedge interposedbetween said edge and the abutment, said wedge having a spring facenormally of greater curvature than the edge of the web but yieldable inresponse to the retracting spring to conform thereto and having itsopposite face in slidable engagement with the abutment, and relativelylight spring means tending to slide said face of the wedge along theabutment but normally prevented by the stress of the retracting spring.

5. In a vehicle brake, in combination with a brake drum and a brake shoewhich includes a flange with a friction lining-and a web with aconcavely curved edge, a flxed abutment spaced from said edge of theweb, a wedge interposed between said edge and the abutment, said wedgehaving transversely extending end portions notched to engage the web ofthe brake shoe, a curved spring member disposed with its end portions insaid notches and with its intermediate arched portion bearing againstthe edge of said web, said spring being adapted to be flexed to conformto the curvature of said edge of the web, the'wedge having an oppositefacein engagement with the abutment, said face extending in convergentrelation to a line connecting the bottoms of the notches in the ends ofthe wedge, and spring means lurging the Wedge in the direction of suchconvergence.

6. In the combination defined in claim l, said abutment being formed asa lug having a notch into which the wedge ts, the notch serving tomaintain the wedge in position as it is shifted in response to saidspring means.

'7. ln a vehicle brake, in combination with a brake drum and a brakeshoe having a ange with a friction lining and a web, a fixed abutmentspaced from said edge of the web, and a wedge member interposed betweensaid edge and the abutment, said wedge having a spring tace whose normalcontour is curved convexly toward the edge of the web, said facebeingyieldable tc conform to said edge and the Wedge having an opposite facein slidable engagement with the abutment, the spring face and saidopposite face of the Wedge extending convergently, spring means urgingthe wedge in the direction of convergence of said faces, and stop meansdisposed for limiting movementl of the wedge in that direction.

8. In the combination defined in claim 1, said abutment being formed as,a lug having a notch into which the wedge fits, the notch serving tomaintain the wedge in position as it is shifted in response to saidspring means, said wedge member having a stop shoulder positioned toengage the abutment lug for limiting movement of the wedge in thedirection of convergence of its said faces.

9. In a vehicle brake, in combination with a brake drum and a brake shoehaving a iiange with a friction lining and a web, a iixed abutmentspaced from said edge of the web and a wedge member interposed betweensaid edge and the abutment, said wedge having a spring face whose normalcontour is curved convexly toward the edge of the web, said face beingyieldable to conform to said edge, and the Wedge having an opposite facein slidable engagement with the abutment, the spring face and saidopposite face of the wedge extending convergently, and spring meansurging the wedge in the direction of convergence of said faces.

- 10. In a vehicle brake, in combination with a brake drum and a brakeshoe having a ange with a friction lining and aweb, a xed abutmentspaced from said edgeof thewebandawedgememberinterposed between saidedge and the abutment, said wedge having a spring face whose normalcontour is curved convexly toward the edge of the web, said face beingyieldable to conform to said edge, and the wedge having an opposite facein slidable engagement with the abutment, the spring face and saidopposite face of the wedge extending convergently, and spring meansurging the wedge in the direction of convergence of said faces, saidwedge, having transversely extending y end portions notched to straddlethe web of the brake shoe and the spring face of the'wedge being formedas a separate curved spring member disposed with its end portions insaid notches and with its intermediate arched portion bearing againstthe edge of the web, said abutment being formed as alug having a notch'which straddles the wedge at its said opposite face, whereby the notchof the abutment and the notches of the wedge serve to maintain thelatter in position as it is shifted in response to said spring means.

` GUIDO v. MABRrro.

